BERLIN -- It was 2002 when Germany granted prostitutes legal status as workers in hopes of improving the safety and fairness of "the world's oldest profession." Since then, the country's sex services industry has grown to include some 200,000 workers with an estimated one million customers paying for sex every day.

When classified ads website craigslist nixed its Erotic Services section in 2009, many speculated that social media networks Twitter and Facebook would pick up much of the slack. Four years later, the prophecy appears to have come true, as social networking sites begin cracking down on profiles offering escort or sex services -- even where prostitution is legal.

"We had covered the area of escort services and prostitution [before] by saying that one could not use a profile to promote anything "unlawful," LinkedIn spokesperson Doug Madey told SmartPlanet.

"However, in some countries, the activity actually is lawful. It was confusing, and a little too general and vague, for our members."

In January, British newspaperThe Times discovered hundreds of unrestricted Facebook pages soliciting sex services last January, raising concerns that children are at risk of exposure. Dozens of pages were removed the day after The Times contacted Facebook, with the social network saying its relies on its community to report inappropriate content before it can take action -- even when a page violates its "clear set of rules."

Twitter was also contacted by the paper, but according to company rules, could only consider content a breach of its terms and conditions if that content were deemed illegal. Disunity about how local laws should apply to international communications platforms could become a crux in discussions among lawmakers about global internet regulation -- a conversation in which companies like Twitter, Facebook and Google are frequently involved.

While sex workers can still be spotted walking the streets of Berlin at 5:30 p.m. on a weekday afternoon, many of the country's prostitutes identify as escorts and solicit their services on various websites, online directories and networks instead. As ReadWriteWeb's Owen Thomas points out, it may be hard to understand how a typically discreet industry such as the escort service could function on mainstream social networking sites where contacts are highly visible to one another.

But Thomas found several suggestions from LinkedIn's search algorithm which reveal that activity is alive and well to some degree: "female escorts," "call girls" and "adult entertainment" all appeared as suggested search terms.

Vanessa Eden -- a self-described erotic coach, who spent a total of six years as an active escort -- confirmed that social networks like LinkedIn are less critical in connecting with clients since members' contacts are readily visible.

"Even in Germany where prostitution and escort services are legal, you still cannot overtly advertise," Eden said. "This makes the industry very dependent on websites and directories," a situation which, Eden acknowledges, could become problematic if a juggernaut like Google -- who has 95 percent market share in Germany -- decided to stop indexing such sites.

And despite its legal status, German prostitution still attracts a lot of crime, raising questions about the effectiveness of 2002's German Prostitution Act on the ground. A recent series of documentaries, reports and interviews by national German media blew the cover off the country's sex tourism industry this spring -- exposing thousands of exploitative brothels and an epidemic of price gouging.

On and offline, the world's oldest profession is booming: Though the statistics are vaguely sourced, Openschools.org created an infographic estimating that 40 million people are currently working -- both voluntarily and involuntarily -- as prostitutes globally. Havoscope.com, a group that collects statistics on black markets, estimates that the sex industry in China generates $73 billion, $27 billion in Spain, and $18 billion in Germany annually.

Meanwhile, escort activity is still relatively prevalent on European-based professional networking site Xing, which places no specific restrictions on activity which is lawful in any country where the platform is available. Members of Xing are also able to contact one another without being officially connected to one another, affording escorts and customers the discretion they would need to do business. Accordingly, a search for "escort" on the site returns some 200 hits.

Xing's Corporate Communications Manager Angela Rittig told SmartPlanet the professional network does not prohibit prostitutes from creating a profile, although it does limit the "scope" of the profile, namely how the user communicates on the site. Pornographic or violence-glorifying materials, solicitation relating to minors or containing explicit sexual references are forbidden, she said.